* Network::Commit
** Removing unnecessary accessors.
** Removing add_refs methods.
* Network::Graph
** Removing unnecessary accessors.
** The 3 times loop of commits don't need.

* Module: Graph -> Network
* Class: JsonBuilder -> Graph

Because model shouldn't know about view logic.

It is fixed that the date label of network graph is broken.

Because not autoloading lib directory at development mode.

When using web hook with credentials secured web resource, one needs to
put the credentials in the hook URL.

If the credentials contain special symbols (e.g. @ or #), it should be
URL-quoted (e.g. %40 instead of @).

But when Gitlab is making a request, it should unquote the symbols
before base64-encoding them.